Fireworthiness properties, namely, one or more of low smoke density, low-toxicity, and flame retardant properties, are important in the manufacture and maintenance of aircraft. It is a significant challenge in design, sourcing, and manufacturing to locate or develop components for manufacturing a gasket for aircraft because of the critical nature of the environment in which they are used. Soft, tacky sealants, which can be used as gaskets, have been known hereto, but these do not fulfill all fire protection standards for certain applications.
Aircraft and sealants used with aircraft are constantly thermally cycled and pressure cycled, and the sealants must maintain their effective environmental sealing properties despite such a radical variation in the environment to which they are subject. Sometimes it is hot and sometimes cold; and sometimes it is dry, or it is a damp or wet environment with a number of different chemicals. Acid rain, for example, can be corrosive especially when exposed to a metallic aircraft surface. For example, a slight pH change in rain may make it slightly acidic and corrosive especially on an aluminum aircraft exterior.
Composite parts used in aircraft construction should comply with standards related to burning behavior of the material.
Thus, it has been proven to be a challenge to design and manufacture sealants that are acceptable in a wide variety of environments over a wide temperature, pressure, and chemical range, which sealants maintain their properties and are also, in a fire, non-toxic and flame retardant (or flame resistance). Moreover, what smoke is produced should be of a low density.